The present invention relates to medical devices that are useful in treating thromboembolic disorders and for removal of foreign bodies in the vascular system.
Thromboembolic disorders, such as stroke, pulmonary embolism, peripheral thrombosis, atherosclerosis, and the like, affect many people. These disorders are a major cause of morbidity and mortality in the United States.
Thromboembolic events are characterized by an occlusion of a blood vessel. The occlusion is caused by a clot which is viscoelastic (jelly like) and is comprised of platelets, fibrinogen and other clotting proteins.
When an artery is occluded by a clot, tissue ischemia (lack of oxygen and nutrients) develops. The ischemia will progress to tissue infarction (cell death) if the occlusion persists. Infarction does not develop or is greatly limited if the flow of blood is reestablished rapidly. Failure to reestablish blood-flow can lead to the loss of limb, angina pectoris, myocardial infarction, stroke or even death.
Occlusion of the venous circulation by thrombi leads to blood stasis which can cause numerous problems. The majority of pulmonary embolisms are caused by emboli that originate in the peripheral venous system. Reestablishing blood flow and removal of the thrombus is highly desirable.
There are many existing techniques employed to reestablish blood flow in an occluded vessel. One common surgical technique, an embolectomy, involves incising a blood vessel and introducing a balloon-tipped device (such as the Fogarty catheter) to the location of the occlusion. The balloon is then inflated at a point beyond the clot and used to translate the obstructing material back to the point of incision. The obstructing material is then removed by the surgeon. While such surgical techniques have been useful, exposing a patient to surgery may be traumatic and best avoided when possible. Additionally, the use of a Fogarty catheter maybe problematic due to the possible risk of damaging the interior lining of the vessel as the catheter is being withdrawn.
Percutaneous methods are also utilized for reestablishing blood flow. A common percutaneous technique is referred to as balloon angioplasty where a balloon-tipped catheter is introduced to a blood vessel, typically through an introducing catheter. The balloon-tipped catheter is then advanced to the point of the occlusion and inflated in order to dilate the stenosis. Balloon angioplasty is appropriate for treating vessel stenosis but is generally not effective for treating acute thromboembolisms.
Another percutaneous technique is to place a microcatheter near the clot and infuse streptokinase, urokinase or other thrombolytic agents to dissolve the clot. Unfortunately, thrombolysis typically takes hours to days to be successful. Additionally, thrombolytic agents can cause hemorrhage and in many patients the agents cannot be used at all.
Another problematic area is the removal of foreign bodies. Foreign bodies introduced into the circulation can be fragments of catheters, pace-maker electrodes, guide wires, and erroneously placed embolic material such as thrombogenic coils. There exists retrieval devices for the removal of foreign bodies, certain of such devices form a loop that can ensnare the foreign material by decreasing the size of the diameter of the loop around the foreign body. The use of such removal devices can be difficult and sometimes unsuccessful.
Various thrombectomy and foreign matter removal devices have been disclosed in the art. However, such devices have been found to have structures which are either highly complex or lacking in sufficient retaining structure. Disadvantages associated with the devices having highly complex structure include difficulty in manufacturability as well as use in conjunction with microcatheter. Other less complex devices tend to pull through clots due to in part to the lack of experience in using the same or are otherwise inadequate in capturing clots or foreign bodies.
Moreover, systems heretofore disclosed in the art are generally limited by size compatibility and the increase in vessel size as the emboli is drawn out in the distal vascular occlusion location to a more proximal location near the heart. If the embolectomy device is too large for the vessel it will not deploy correctly to capture the clot or foreign body and if too small in diameter, it cannot capture clots or foreign bodies across the entire cross section of the blood vessel. Additionally, if the embolectomy device is too small in retaining volume, as the device is retracted, the excess material being removed can spill out and be carried by flow back to occlude another distal vessel.
Thus, there exists a need for an extraction device that can be easily deployed into the circulatory system for the effective removal of clots and foreign bodies. There is also a need for a device which could be used as a temporary arterial or venous filter to capture and remove thromboemboli formed during endovascular procedures.
The present invention is directed to devices that are useful in removing clots and foreign bodies from vessels. Various embodiments and method of use are disclosed for the effective removal of clots or foreign bodies. It is contemplated that the present invention may be used in all vasculature including the neurovasculature.
In one aspect of the invention, an elongate generally linear wire is provided for the removal of certain types of undesirable matter found in a blood vessel. The elongate generally linear wire is placed within the undesirable matter and rotated to thereby catch the matter and wind it about the wire. Withdrawing the wire within a receiving tube or directly through the vessel operates to extract the undesirable matter from the patient""s vasculature.
In another aspect of the invention, a staged filter/emboli extractor is provided to remove clots or foreign material from a vessel. In one embodiment, a plurality of spaced-apart radially extending structures are configured on an elongate wire or tubular mandrel proximal a distal end of the mandrel. The radially extending structures are characterized by increasing in size from the most proximal structure to the most distal structure. In a presently preferred embodiment, each of the radially extending structures are in the form of a plurality of loops or petals arranged in an annular radial array about the circumference of the mandrel. In an alternative embodiment, each of the plurality of loops or petals originate from a common side of the mandrel and can be concentrically arranged.
In yet a further aspect of the invention, a knitted or mesh structure is provided for the removal of clots or foreign material from a blood vessel. The knitted or mesh structure is configured near the distal end portion of an elongate wire or tubular mandrel. In one presently contemplated embodiment, the knitted or mesh structure is affixed in a conventional manner to the distal end of the mandrel. In another presently contemplated embodiment, the knitted or mesh structure surrounds a distal portion of the mandrel and may additionally embody structure enabling one end of the knitted or meshed structure to be translated longitudinally with respect to its other end which is held fixed. The knitted or mesh structures disclosed are further characterized by having open or closed ends or a basket-like configuration.
The invention also includes an elongate tubular delivery catheter with at least one lumen for receiving an extractor device and for retaining the distal portion thereof in a reduced profile. The delivery catheter may be used in conjunction with an elongate insertion catheter that is configured to be introduced into a large vessel and advanced within a patient""s vasculature.
Generally, the clot is extracted from a vessel by capturing the same and withdrawing the clot or foreign material proximally until it can be removed or released into a different vessel that does not perfuse a critical organ. The structure disclosed can also be used as a temporary arterial or venous filter to capture and remove thromboemboli formed during endovascular procedures. By removing the device from the body, the clot or foreign material is also removed.
Other features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention.